Method of manufacturing hollow articles composed of resin impregnated yarn windings



May 14, 1957 H. s. DALEY ET AL METHOD OF MANUFACTURING HOLLOW ARTICLESCOMPOSTO OF RESIN IMPREGNATED YARN WINDINGS Filed NOV. 24, 1954INVENTORS BY Horace SDa/ey IHETHOD F MANUFACTURING HOLLOW ARTI- CLESCOMPOSED 0F RESIN IMPREGNATED YARN WINDINGS Horace S. Daley, Clifton,and Edward A. Wentz, Mont clamN. J., assignors to SpecialtiesDevelopment Corporation, Belleville, N.v J., a corporation of New JerseyApplication November 24, 1954, Serial No. 471,022

' 1 claim. (ci. 154-83) The present invention relates to a method of andapparatus for manufacturing hollow articles partially composed of resinimpregnated yarn windings, and, more particularly, to the conditioningand handling of the yarn preliminary to -its application as a winding inthe manufacture of receptacles, such as cylinders or spheres and tubesor conduits, for confining uid medium under high pressure.

It has been proposed to manufacture receptacles of the foregoingcharacter by applying windings of resin impregnated yarn on an innershell or a form, and curing 'the resin to provide a Wall consisting ofresin and yarn and having a thickness to withstand high pressure. Suchreceptacles are much lighter in weight than similar receptacles formedof metal, but, heretofore, difficulty has been encountered in producingsuch receptacles which can safely withstand the high pressures at whichit is desired to confine the medium and which can survive the pressurefluctuations to which such receptacles are subjected in the normal usethereof. The difficulties which have rbeen most pronounced are that thebursting strength of such receptacles-is well below that desired andthat the wall composition fatigues too quickly whensubjected to fthepressure fluctuations the yreceptacles are required to withstand underpresent safety regulations. In accordance with the present invention, ithas now -been discovered that localized stresses caused by smallimperfections in the winding are instrumental in greatly weakening suchreceptacles. It has been found that uneven dryness and tensioning of theyarn or strands of yarn and uneven impregnation thereof primarily arethecause of the aforementioned diiiiculties; and rthat uneven impregnationis induced by uneven dryness and uneven tensioning, and that unevendryness affects proper tensioning.

Accordingly, an object of the present invention is to provide `a methodof and apparatus for producing high pressure medium` confiningreceptacles having greater bursting strength and greater'fatigueresistance than receptacles of comparable wall thickness heretoforeproduced.

Another object is to provide such method and apparatus which conditionthe lwindings in a manner to uniformly tension and impregnate the same,whereby localized weaknesses in the resulting receptacles are greatlyminimized or entirely eliminated.

A yfurther object is to provide such method and apparatus which aresimple, practical and economical and do not slow down production.

Other and `further objects of the invention will be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claim, and various advantages notreferred to herein will occur to one skilled in the art upon employmentofthe invention in practice.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description, and

was at@ ice is shown in the accompanying drawing, forming a part of thespecification, wherein:

means and steps utilized in carrying out the present invention.

Fig. 2 is a schematic plan View lillustrating apparatus in accordancewith the invention.

As shownin Fig. l of the drawing, theA essential means of the apparatusfor performing the steps of the method utilized in connection withpracticing the present invention comprise a creel 10 for supplyingstrands of yarn including means for uniformly tensioning the strands,means 1l for drying the strands, means 12 for resin impregnating t-hestrands, means 13 for grouping together the strands, means 14 forremoving excess resin lfrom the strands, and means 1S for finallyapplying the resin impregnated strands as windings to produce the wallstructure of hollow receptacles. The order of arrangement of certain ofthese means and the corresponding -method steps performed thereby can bevaried, whereby the present invention is in no Way to be lirnited by theillustrative embodiment herein. For example, the strands may be driedprior to tensioning the same, and the strands may be grouped togetherafter removing the excess resin therefrom.

ln Fig. 2, the aforementioned means arev illustrated schematically, and,as shown therein, the creel includes a plurality of yarn packages 20each adapted to Supply a strand or end of yarn S. Four of such packagesare shown by way of example, although any suitable number greater thanfour may be utilized depending on yarn size and the ltype of winding tobe applied. Such a creel may be of any conventional design and need notbe illustrated in detail.

I-f desired, the yarn drying means 11 may be associated with the creelby providing an enclosure 21 for the creel having an inlet 22 and anoutlet 23 for heated air acting as a drying medium, and having a slit 24through which The impregnating means 12 or the zone in which im-Apregnation takes place may include a receptacle 26 containing liquidresin and suitable rolls 27 forpassing the strands, through the resin orapplying the resin to the strands by coming in contact therewith., Suchimpregnating `devicesare well known and need not he illustrated ordescribed in detail. y v

in order to assure uniform impregnation of the strands and theindividual laments or fibers of which the strands may be composed, thestrands are maintained out of contact with each other while in theimpregnating zone. This may be accomplished by passing the strandsbetween sets of spaced apart pins or a pair of combs 28 and 29 at eachend of the impregnating bath.

The excess resin removing means 14 may be a blade or wiper 3d over whichthe strands pass in contact therewith, or, alternatively conventionalsqueeze rolls could be used for this purpose. If desired, the strandsare maintained in the aforementioned spaced apart relation to providefor uniform resin impregnation of the strands `after the excess isremoved by the comb 29 at the incoming side of the means 14 and a comb30 at the outgoing side. Preferably, the amount of resin permitted toremain on the yarn is just about sufficient to coat the individualfibers or filaments thereof with a film adapted to prevent abrasiontherebetween and between strands Patented May 14, 19.574.

o f yarn. This amount of resin is effective to bondY they yarn uponcuring of the resin and to produce a composition having a strength., Y Yv The strand grouping means; 13, may beaguide 32 ysuch as a pair ofpins, a ring, kor.converging tube for bringing thev strandstogether,"and may include a hanged pulley or wheel 33 for arranging thestrands into a ribbon-like bandv adapted tov be passed through a guide34 and applied as the winding.

The` strand applying means .15 is illustrated herein as a Winder forapplying a hoop Winding on a cylindrical surface ofa receptacleR,.although such means could be winders for applyingA hoop and/orend-over-end windings, on. cylinders or great circle windings onspheres.

The Winder shown herein comprises a spindle 35 on which the receptacleis mounted for rotation about its longitudinal axis, and a'yarn traverse36 including a guide 37 forxpositioning the winding on the: receptacle.The winder'serves to withdrawthe strands from the creel and to draw thesame through the impregnating bath and the grouping means.

, After the winding is applied to provide` a wall of desired ythickness, the resin is cured by placing the receptable in an oven foratleast about 4 hours, maintained at a temperature of about212 F.,whereby a solid wall structure composed of yarn and resin is produced.By conditioning the yarn in the manner described herein, it Was foundthat the wall structure consisted of between 80% to 85% yarn and 20% to15% resin. Cylinders having a capacity of about 500 cubic inches wereconstructed of such yarn-resin composition and were found toV safely;

withstand: internal pressures of about 3000 pounds per square inch inservice and G00 pounds per square inch under test, and exhibited nosigns of fatigue after being alternately pressurized from 0 to 3000pounds per square inch through 5000 cycles in about 24 hours.

The term yarn is used herein in a broad sense and is intended to includeyarns formed of natural or synthetic fibers or filaments suitable forimpregnation. Fiber glass yarn is preferred because of its high tensilestrength and resistance to heat, although other types of high tenacityyarns may be usedto good advantage, for example, multiiilament yarnsformed of materials such as nylon, vinylidene chloride, polyester andexible metal.

Fiber glass yarn has a tensile strength ofbetween about 300,000 poundsper square inch, a specic gravity of about 2.57, and is available'invarious sizes. For example, sixteen. strands of size 140 (14,000 yardsper pound, 204 filaments) fiber glass yarn, impregnated and groupedtogether in accordance with the method of the present invention, providean excellent winding.

A wide variety of thermosetting or thermoplastic resins' may beutilized, for example, epoxy or modied epoxy resins, polyester typevresins and acrylic resins which are available in liquid form. Also,silicone resins andl phenolic resins modied with a solvent may be used.A suitable wetting agent may be admixed in the resin to expediteimpregnation of the yarn. Such resins upon curing are converted into asolid mass having a tensile high yarn content and high structurat 15% byweight of. the impregnated strands upon curing l of the resin whichamount is sufficient to coat the indi# strength on the order of about5000 to 8000 pounds per` square inch.

A specic example of practicing the method in ac cordance with presentinvention comprises supplying sixteen strands of size 140 ber glass yarnwhich have been uniformly dried and tensioned to' about l0 grams,passing the strands through Vliquid epoxy resin while maing, taining thestrands apart to assure uniform impregna? tion thereof, removing excessresin from the strands, grouping the strands together in a ribbon-likeband, applying the band to a shell as a winding under a tension' ofabout 3 to l0 pounds, and curing the resin to produce a wall structuresurrounding the shell composed of` about 85% fiber glass and 15%insoluble resin. r 1

From the foregoing description it will b e seen that the presentinvention providesV a simple,practical and economical method of andapparatus for producing strong and durable wall structures forreceptacles consisting of yarn and resin.

As various changes may be made in the form, con` struction andarrangement of the partsV herein, 'without departing from the spirit andscope of the invention andl without sacrificing any ofy its advantages,it is to be understood that all matter herein is to be interpreted asillustrative and not in any limiting sense.

We claim:

The method of manufacturing hollow articles for confming afiuid mediumunder pressure, which method comprises simultaneously exposing aplurality of strands composed of yarn filaments to a drying atmosphereto uni-v formly remove moisture therefrom, individually tension-V ingthe strands'. to place the same under substantially con# stant uniformtension on the order of about 5 to l5 grams, individually impregnatingthe strands` immediately after l tensioning of the same bysimultaneously applying a liquid resin thereto from a common .,source,removing resinfrom the strands to leave an amount of resin of aboutvidual laments and prevent abrasion therebetween, grouping together theimpregnated strands into a ribbonlike band, applying the band as awinding of a plurality of layers to form a hollow article, and curingthe winding to provide a wall for the hollow article having a yarncontent of about 85% by weight, the wall of the hollow article beingcharacterized in that it canV safely withstand internal pressure ofabout 5000 p. s. i. and exhibits no sign of fatigue after beingalternately pressurized from 0' to 3000 p. s. i, through 5000 cycles inabout.

twenty-four hours.

References Cited in the le of this patent UNITED STATES PATENTS

